First of all, Xiangzi lived in China society in the late Qing Dynasty, which was an era of disparity between the rich and the poor and social injustice. Xiangzi was born in poverty. He didn't get a good education and training, so he had to rely on his own efforts to make a living. However, in the process of working hard and saving money to buy a house, he encountered various injustices and obstacles, which made him full of anger and dissatisfaction with society.
Secondly, there is serious gender discrimination and moral decay in Xiangzi's society. In order to survive, Xiangzi had to accept the indenture of prostitution and become the male companion of prostitutes, which was discriminated and rejected by society. He fell in love with Wang Xiuying, but because of poverty and low status, he couldn't be with her, which made him feel lonely and helpless.
In addition, Xiangzi's personal shortcomings are also one of the reasons for his tragedy. He is greedy for money, selfish, impulsive and irrational, which makes him often make wrong decisions in his life, and finally leads to his tragic ending.
To sum up, Xiangzi's tragedy is mainly caused by social injustice, human ills and personal defects. This also reflects the social ills in China at that time and the grim reality faced by ordinary people.